diff --git a/direct/src/fsm/FSM.py b/direct/src/fsm/FSM.py
index 94bccf491e..2fbd5ccde9 100644
--- a/direct/src/fsm/FSM.py
+++ b/direct/src/fsm/FSM.py
@@ -62,29 +62,37 @@ class FSM(DirectObject.DirectObject):
 
     def filterRed(self, request, args):
         if request in ['Green']:
-            return request
+            return (request,) + args
         return None
 
     def filterYellow(self, request, args):
         if request in ['Red']:
-            return request
+            return (request,) + args
         return None
 
     def filterGreen(self, request, args):
         if request in ['Yellow']:
-            return request
+            return (request,) + args
         return None
 
     As above, the filterState() functions are optional.  If any is
-    omitted, the defaultFilter() method is called instead.  The
-    default definition of defaultFilter() always returns None, thus
-    disallowing all unexpected transitions.  This default behavior may
-    be overridden in a derived class.
+    omitted, the defaultFilter() method is called instead.  A standard
+    implementation of defaultFilter() is provided, which may be
+    overridden in a derived class to change the behavior on an
+    unexpected transition.
 
-    FSM.state may be queried at any time other than during the
+    If self.defaultTransitions is left unassigned, then the standard
+    implementation of defaultFilter() will return None for any
+    lowercase transition name and allow any uppercase transition name
+    (this assumes that an uppercase name is a request to go directly
+    to a particular state by name).
+
+    self.state may be queried at any time other than during the
     handling of the enter() and exit() functions.  During these
-    functions, FSM.state contains the value None (you are not really
-    in any state during the transition).  At other times, FSM.state
+    functions, self.state contains the value None (you are not really
+    in any state during the transition).  However, during a transition
+    you *can* query the outgoing and incoming states, respectively,
+    via self.oldState and self.newState.  At other times, self.state
     contains the name of the current state.
 
     Initially, the FSM is in state 'Off'.  It does not call enterOff()
@@ -191,11 +199,24 @@ class FSM(DirectObject.DirectObject):
 
     def defaultFilter(self, request, args):
         """This is the function that is called if there is no
-        filterState() method for a particular state name.  By default,
-        the filter defined here in the base class always returns
-        None, disallowing any transition.  Specialized FSM's may wish
-        to redefine this default filter (for instance, to always
-        return the request itself, thus allowing any transition.)."""
+        filterState() method for a particular state name.
+
+        This default filter function behaves in one of two modes:
+
+        (1) if self.defaultTransitions is None, allow any request
+        whose name begins with a capital letter, which is assumed to
+        be a direct request to a particular state.  This is similar to
+        the old ClassicFSM onUndefTransition=ALLOW, with no explicit
+        state transitions listed.
+
+        (2) if self.defaultTransitions is not None, allow only those
+        requests explicitly identified in this map.  This is similar
+        to the old ClassicFSM onUndefTransition=DISALLOW, with an
+        explicit list of allowed state transitions.
+
+        Specialized FSM's may wish to redefine this default filter
+        (for instance, to always return the request itself, thus
+        allowing any transition.)."""
 
         if request == 'Off':
             # We can always go to the "Off" state.